context: Add SSH_AGENT_PID and SSH_AUTH_SOCK to initial environment

This allow to use the host-side SSH agent when cloning protected
repositories via kas. We already do this for the build environment.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>

kas/context.py

@@ -102,7 +102,8 @@ class Context:
             logging.warning('kas: No supported distros found in %s. '
                             'No default locales set.', distro_bases)
 
-        for key in ['http_proxy', 'https_proxy', 'ftp_proxy', 'no_proxy']:
+        for key in ['http_proxy', 'https_proxy', 'ftp_proxy', 'no_proxy',
+                    'SSH_AGENT_PID', 'SSH_AUTH_SOCK']:
             val = os.environ.get(key, None)
             if val:
                 self.environ[key] = val